Circuit breaker



A118. 1942- R. H. SWINGLE 2,293,179

CIRCUIT BREAKER Filed Feb. 26, 1941 WITNSSES: 45 INVENTQR 3;? a E0 40/; Hfiwxng/Q.

; '7 1' M, t W! ATTORNE Patented Aug. 18, 1942 CIRCUIT BREAKER Ralph H. Swingle, Pittsburgh, Pa., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application February 26, 1941, Serial No. 380,636

17 Claims.

The invention relates to circuit interrupters and, more particularly, to circuit breakers which are manually operable to open and close the circuit and which are automatically operated to open the circuit in response to predetermined abnormal conditions.

An object of the invention is the provision of an improved circuit breaker having a manual operating handle operable to cause opening or closing of the contacts and a current responsive snap-acting bimetal element operable to automatically open the contacts in response to predetermined overload conditions even though the handle is held in closed position.

Another object of the invention is the provision of acircuit breaker wherein the contacts are automatically opened by a snap bimetal disc and are arranged to be trip free of the manual operating handle so that they cannot be held closed against an overload.

Another object of the invention is the provision of a. circuit breaker wherein contacts are automatically opened in response to predetermined overload conditions by a snap-acting bimetal element and cannot be reclosed after automatic operation until the mechanism has been manually reset by moving the operating handle to open position.

Another. object of the invention is the provision of an improved circuit breaker having a current responsive snap-acting bimetal element for automatically opening the contacts and an operating handle operable to cause movement of the bimetal element to manually open and close the contacts. 7

Another object of the invention is the provision of a circuit breaker as previously described wherein the contacts cannot close after automatic opening even though the handle is held closed and the bimetal element has cooled.

Another object of the invention is the provision of a circuit breaker as previously described which is simple and inexpensive to manufacture and.

Figure 1 is a sectional view of the circuit breaker with the parts shown in the closed-circuit position;

Fig. 2 is a view similar to Fig. 1 but showing the breaker in the manually-opened position;

Fig. 3 is a view similar to Fig. 1 but showing the breaker in the tripped-open position;

Fig. 4 is a sectional view of a modification of the invention whereby greater separation of the contacts is obtained;

Fig. 5 is a plan view of the bimetal disc and contacts carried thereby of the modification shown in Fig. 4;

Fig. 6 is a sectional view of a modified form of the thermal switching element; and

Fig. 7 is a plan view of the thermal switching element shown in Fig. 6.

Referring to Figs. 1 to 3 of the drawing, the circuit breaker of the present invention comprises a casing 9 of molded insulated material and a cooperating cover I I also of molded insulated material which is removably secured to the casing 9 at the open side thereof. A pair of terminal strips l3 and 15 are mounted by screws I! in a pair of recesses provided therefor at the opposite ends of the casing 9. A pair of stationary contacts 19 are secured to the inner ends of the terminal strips 13 and IS. The other end of each terminal .strip extends outside of the casing 9 for connecting the breaker to an electrical circuit.

A movable switch member comprising a snapacting disk 23 of bimetallic material is movably supported within the casing at its center on a headed bolt 25. The bolt 25 is slidably mounted in a central opening 2! in the base of the casing 9 and has a lock nut 28 threaded on the inner end thereof for limiting movement of the bolt 25 and disk 23 toward the cover H.

The bimetal disk 23 is formed of two united disks of sheet metal pressed into a concave form, the composite piece being capable of being sprung with a snap-action from either one to the other of two opposite or reversely flexed positions without having any intermediate position of stability. The metals of the united disks comprising the disk 23 are selected to have dififerent coefficients of thermal expansion, and the two parts are proportioned and constructed so that the disk 23 will snap from a normal flexed or concave position, as shown in Fig. 1, to an opposite flexed or concave position, as shown in Fig. 3, when the disk is heated a predetermined amount by CW erload current. The construction of the d1sk I9 is also such that it will remain in the opposite flexed or concave position shown in Fig. 3 after the disk has returned to its normal temperature.

and until it is manually reset to its normal flexed or concave position, as shown in Fig. 2.

A pair of movable contacts 29 are secured to the bimetal disk 23 adjacent the edge thereof on opposite sides of the center for en aging the stationary contacts l8 whenthe bimetal disk 23 is in the closed-circuit position shown in Fig. 1.

The disk 23 and movable contacts 29 when in 4 'closed-positioncomplete the circuit between the stationary contacts -|9v so that the disk is traversed by the current flowingrin the circuit. At

-When an overload occurs in the circuit and continues fora length of time suflicient to heat the bimetal disk a predetermined amount, the bimetal disk operates to snap from its normal flexed or upwardly-concave position shown in Fig. 1 to the opposite flexed or downwardlyconcave position shown in Fig. 3. This operation normal rated current the bimetal disk. 23 is, not

heated a suffi'cient amount to snap away from its normal'flexed position;

-A compression spring 3| encircles the bolt 25 and is disposed betweenthe base of the casing 9 and the'central portion'of the bimetal di'sk23. The spring 3| acts to biasthe bimetal disk 23 in a direction toward the cover so as to close the contacts of thebreaker if the bimetal disk of the disk causesthe' movable contacts 29 to separate from the stationary contacts l9 andinterrupt the circuit irrespective of the-position of the operating handle 33; thatis, even though the operating handle is held" in closed position. This makesthe device a trip-free. circuit breaker. The bimetal disk 23 remains inthe operated position shown in Fig. 3 even after the disk has cooled to its normal temperature; thus precluding closing of the contacts until after the disk. isman is in its normal flexed condition. The 'lock nut 28 is positioned on the bolt so that the bimetal disk 23 does not bearagainstthe head of the bolt 25 when the parts are in closed-circuit position. Thus, the compression spring 3| 5 provides a predetermined contact pressure between the movable and stationary contacts.

An operating handle 33 of molded insulating material is mounted on a pivot pin 35 which is rotatably supported by the said walls of the casing 9. The ends of the pivot pin 35 are seated in bearing recesses provided in the side walls of the casing 9, and the operating handle is maintained in mounted position by means of the cover H which has a central opening for accommodating the operating handle. The operating handle 33 is provided with a cam portion 31 which extends within the casing and is adapted to engage the head of the bolt 25. The cam portion 31 is shaped so that when the operating handle is moved in a clockwise direction from the closed position shown in Fig. 1 to the open position shown in Fig. 2, the bolt 25'and bimetal disk 23 are moved inwardly to open circuit position against the force of the compression spring 3|. The inner end of the operating handle has a flattened surface 32 which cooperates with the head of the bolt 25 to maintain the parts in opencircuit position until the handle is again operated to close the breaker. When the handle 33 is moved to the open position shown in Fig. 1, the compression spring 3| acts to move the bimetal disk 23 to closed position to close the contacts of the breaker.

The interior of-the casing 9 is formed to probase of the casing for engaging the outer edge of the bimetal disk 23 when the disk is moved to open-circuit position by the operating handle 33.

The operation of the circuit breaker is briefly as follows: To manually open the circuit breaker the operating handle 33 is moved in a clockwise direction to open position.' This movement of the handle moves the bolt 25 and bimetal disk 23 inwardly against the force of the spring 3| to effect separation of the movable contacts 23 from the stationary contacts IS. The circuit breaker is retained in open-circuit position by the engagement of the flattened inner end 32 of the handle 33 with the head of the bolt 25.

. To manually close the circuit breaker the operating handle 33 is moved in a counterclockwise vide a central annular shoulder 39 adjacent the ually reset to its normal flexed position.

In order to manually reset the'bimetal diskto moves the bolt 25 inwardly, pressing the central portion of the bimetal disk towards the base of the casing. Due to the fact that the outer edge of the bimetal disk bears against the annular shoulder 39, the movement of the operating handle to the open position springs the disk 23 back to its normal flexed or upwardly-concave position, as shown in Fig. 2. After the bimetal disk has thus been reset, the circuit breaker may be reclo'sed bymoving the operating handle to closed position.

The trip characteristic of the circuit breaker may be calibrated or adjusted by means of a nut 44 which is threaded on a fixed sleeve 46 secured to the base of the casing 9 in line with the opening for the bolt 25. The bolt" 25 is slidable in the fixed sleeve 46, and the inner end of the compression spring 3| bears on the adjusting nut 44. When the nut 44 is adjusted upwardly or downwardly on the fixed sleeve 46, the force of the spring 3| against the bimetal disk is increased or decreased, thereby altering the tripping point of the bimetal disk ,23.

In the modification of the invention as shown in Figs. 4 and 5, a greater contact separation is obtained by having the movable contacts 29 mounted on the outer ends of a pair of arms 4| of conducting material which are secured to the edge of the snap-acting bimetal disk 23 on opposite sides of the center. a given movement of the bimetal disk 23 will give an amplified contact movement due to the long lever arm on which the contacts are mounted. 1

The remaining structure of the modification shown in Fig. 4 is identical to that of the original embodiment, and the same reference characters have been applied to the corresponding parts. If desired, the arms 4| which carry the movable contacts may be selected to have a higher elecmodification, the snap-acting bimetal disk 23 is direction to closed position. During this moveadapted to be heated by a separate electrical With this construction heating resistance 43 which is electrically connected between the movable contacts 29'. The heating resistance 43 comprises a flexible resistance wire of generally sinusoidal shape which is carried by the bimetal disk 23' and insulated,

therefrom by thin mica plate 45. The movable contacts 29' are electrically insulated from the bimetal disk 23' by means of insulating washers 41. The remaining structure of the modification shown in Figs. 6 and 7 is identical to that of the original embodiment and the operation thereof is the same except that in this instance the bimetal disk is heated in response to the current flow by the separate heating resistance 43 instead of by current flow through the bimetal disk itself.

While the invention has been disclosed in accordance' with the provisions of the patent statutes, it is to be understood that various changes in the structural details and arrangement of parts thereof may be made without departing from some of the essential features of the invention. It is desired, therefore, that the language of the accompanying claims be given the broadest reasonable construction permissible in the light of the prior art.

I claim as my invention:

1. A circuit breaker comprising relatively movable contacts, operating means therefor comprising a thermally-responsive snap-acting bimetal element, and manually operable means for moving said bimetal element to manually open and close said contacts, said bimetal element being operable when heated a predetermined amount to snap from one position to another and cause automatic opening of said contacts even though said manually operable means is held in closed position, said contacts when automatically opened by said bimetal element remaining open even though said manually operable means may be held in closed position and said bimetal element has cooled to its normal temperature.

2. A circuit breaker comprising relatively movable contacts, operating means therefor comprising a thermally-responsive snap-acting bimetal element heated in response to the current of the circuit, and means including a pivoted handle for moving said bimetal element to manually open and close said contacts, said bimetal element when heated a predetermined amount by overload current operating to cause automatic opening of said contacts irrespective of the position of said handle, said contacts when automatically opened remaining open even though said handle is held in closed position and said bimetal element has cooled to normal temperature.

3. A circuit breaker comprising relatively movable contacts, operating means therefor comprising a thermally-responsive snap-acting bimetal element, and manually operable means for moving said bimetal element to manually open and close said contacts, said bimetal element when heated a predetermined amount operating to snap from one position to another to cause automatic opening of said contacts irrespective of the position of said manually operable means, the first said operating means being inefiective to close said contacts after automatic opening even though said bimetal element has cooled to normal temperature until said manually operable means is manually moved to reset said bimetal element to said one position.

4. A circuit breaker comprising relatively movable contacts, operating means therefor comprising a thermally-responsive snap-acting bimetal element adapted to snap from one position to another of two oppositely flexed positions, said element being heated in response to the current of the circuit, means movably mounting said bimetal element, handle means for moving said bimetal element to manually open and close said contacts, said bimetal element when heated a predetermined amount by overload current operating to snap from its normal flexed position to an opposite flexed position to cause automatic opening of said contacts irrespective of the position of said handle means, said operating means being ineffective to close said contacts after automatic opening of said contacts even though said bimetal element has cooled to normal temperature until said handle means is manually moved to reset said bimetal element to its normal flexed position.

5. A circuit breaker comprising relatively movable contacts, operating means therefor comprising a thermally-responsive snap-acting bimetal element and handle means for moving said bimetal element to manually open and close said contacts, said bimetal element when heated a predetermined amount operating to snap from a normal flexed position to an opposite flexed position to cause automatic opening of said contacts irrespective of the position of said handle means, said bimetal element when operated precluding closing of said contacts until said handle means is manually moved to reset said bimetal element to its normal flexed position. v

6. A circuit breaker comprising relatively movable contacts, operating means therefor comprising handle means for manually opening and closing said contacts, a thermally-responsive snapacting bimetal element operable when heated a predetermined amount to snap from a normal flexed position to an opposite flexed position to cause automatic opening of said contacts irrespective of the position of said handle means, said bimetal element being resettable to its normal flexed position by manual movement of said handle means towards open position, and said bimetal element after automatically operating said contacts preventing closing of said contacts until said element has been reset to its normal flexed position by manual operation of said handle means.

7. A circuit breaker comprising relatively movable contacts, operating means therefor comprising handle means for manually opening and closing said contacts, a thermally-responsive snapacting bimetal element operable when heated a predetermined amount to snap from a normal flexed position to an opposite flexed position to cause automatic opening of said contacts irrespective of the position of said handle means, said bimetal element when operated to said opposite flexed position remaining in said opposite flexed position after it has cooled to normal temperature and preventing closing of said contacts until said element is manually reset to its normal flexed position.

8. A circuit breaker comprisinga first contact, a thermally-responsive snap-acting bimetal ele-. ment carrying a second contact for engaging said first contact, an operating handle mounted solely for pivotal movement on a fixed pivot, an operating spring engaging a stationary support at one end and acting at all times to bias one of said contacts in one direction, said handle being operable to cause opening or closing of said contacts, and said bimetal element being operable when heated a predetermined amount to cause opening of said contacts irrespective of the posi tion of said handle.

9. A circuit breaker comprising a first contact,

tion, amovable contact carried by saidbimetal elementfor cooperatingwith said stationary contact,.means movably mounting said .bimetal elea thermally-responsive snap-acting bimetal eleating means, said bimetal element when heated a predetermined amount operating to cause auto-1 matic opening of said contacts irrespectivev of the position-oi said manual operating means. 7 10. A circuit. breaker comprising relatively movable contacts, operating means therefor comprising a thermally-responsive snap-acting bimetal element heated in response to the current of the circuit, manually operableoperating means for 1 moving said bimetal element to open and stationary contacts, a snap-acting bimetal disk close said contacts, said bimetal'element when heated a predetermined amount by overload cur-.

rent operating to snap from a normal position to j a second position tocause automatic opening of said contactsirrespective ofthe position of said manual operating means and remaining in said second position after it has cooled to normal temperature to preclude closing of said contacts until said element has been manually reset to its initial position. 11. A circuit breaker comprising a stationa contact, a thermally-responsive snap-acting bimetal element having a normal flexed position, a movable contact carried by said bimetal element for cooperating with said stationary contact,

means movably mounting said bimetal element, a

spring for biasing said bimetal element to engage said contacts if said element is in its normal flexed position, a manual operating member for moving said bimetal element to open and close said contacts, said bimetal element when heated a predetermined amount operating to snap from its normal flexed position to a second position to cause automatic opening of said contacts irrespective of the position of said operating member, and said bimetal element remaining in said second position after it has cooled to its normal temperature to preclude closing of said contacts until said element is manually reset to its normal flexed position.

12. A circuit breaker comprising a stationary contact, a thermally-responsive snap-acting bielement to open and-to close said contacts, said I bimetal element when heated a predetermined amount operating to snap from its normal flexed position to a'second position to cause automatic opening of said contacts irrespective of the position of said operating handle and remaining in said second position after it has cooled'to its normal temperature to preclude closing of said contacts until said bimetal element has been manually reset to its normal flexed position, said operating handle being operable when movedtoward open position to reset said bimetal elemen to its normal flexed position.

I 13. A circuit breaker comprising a stationary contact, a thermally-responsive snap-acting bimetal element heated in response to the current of the circuit and having a normal flexed posiment, a spring biasing said bimetal element to engage saidcontacts, a manually operable cam lever for moving said'bimetal element to manually open or close said contacts, said bimetal element when heated a predetermined amount by overload current operating to snap from its normal'flexed position to an opposite-flexed position to cause opening of said contacts irrespective of'the position of said cam leverand remaining in said opposite position after it has cooled to normal temperature to prevent closing of said contacts until said'bimetal element hasbeenmanually reset to its normal flexed position, said .cam lever being operable upon movement thereoi toward open position to reset said bimetal element to its normal flexed position.

14. A circuit breaker comprising a pair' of 'havinga normal flexed position, a pair of movable contacts carried by said disk for engaging' manually operable cam lever for moving said disk I to manually open and close said contacts, said bimetal disk when heated a predetermined amount by overload current operating to snap from its normal flexed position to an opposite flexed position to cause automatic opening of said contacts irrespective of the position of said cam lever, and remaining in said opposite position after it has cooled to normal temperature to preclude closing of said contacts until said bimetal disk is manually reset to its normal flexed position.

15. A circuit breaker comprising a pair of stationary contacts, a snap-acting bimetal disk having a normal flexed position, a pair of movable contacts carried by said disk adjacent the edge for engaging said stationary contacts, a spring for biasing said bimetal disk to close said contacts, a pivoted cam lever operable to cause movement of said bimetal disk to manually open or close said contacts, said bimetal disk when heated a predetermined amount'by overload current operating to snap from its'normal flexed positionto an opposite position to cause opening of said contacts i'rrespectivefof the position of said cam lever, said bimetal disk remaining in said opposite position after'ithas cooled to its normal temperature to preclude closing of said contacts until said disk has been manually reset to its normal flexed position, said cam lever being operable when moved to open-position to cause resetting of said disk to its normal flexed position. 16. A circuit breaker comprising a pair of spaced stationary contacts; a snap-acting bimetal disk'having a normal flexed position, a pair of arms of conducting material secured to said disk adjacent the edge thereof and extending outwardly therefrom on opposite sides of the center, a pair of movable contacts mounted on the free endsof said arms for engaging said stationary contacts,a manual operating member for moving said disk to manually open or close the contacts, said bimetal disk when heated a predetermined amount by overload current operating to snap from its normal flexed position to an opposite flexed position to automatically open the contacts irrespective of the position of said manual operating member.

17. A circuit breaker comprising a pair of stationary contacts, a snap-acting bimetal disk having a normal flexed position, a pair of movable contacts carried by said disk adjacent the edge and insulated from said disk, an electric heating element carried by said disk having its terminals connected to said movable contacts, a manual operating member for moving said disk to manually open or close the contacts, said bimetal disk when heated a predetermined amount by overload current operating to snap from its normal flexed position to an opposite flexed position to cause automatic opening of the contacts irrespective of the position of said operating member.

RALPH H. SWINGLE.

DISCLAIMER 2,293,179.Ralph H. Swingle, Pittsburgh, Pa. CIRCUIT BREAKER. Patent dated August 18, 1942. Disclaimer filed February 17, 1944, by the assignee, Westinghouse Electric cf: Manufacturing Company. Hereby enters this disclaimer to claims 8, 9, and 16 of said patent.

[Ofiicial Gazette March 21, 1944] DISCLAIMER 2,293,179.Ralph H. Swingle, Pittsburgh, Pa. CIRCUIT BREAKER. Patent dated August 18, 1942. Disclaimer filed February 17, 1944, by the assignee, Westinghouse Electric dc Manufacturing Company.

Hereby enters this disclaimer to claims 8, 9, and 16 of said patent.

[Ofiicial Gazette March 21, 1944] 

